In an automatic coal stoker of Potts (U.S. Pat. No. 4,662,290 of May 5, 1987) employs the pusher assembly, operated by a cam assembly 24, which reciprocally shifts step-like protuberance 58 and provides an enshrouded pusher which is resistant to attacks of such coal acids. The intermittent pusher assembly of the Potts patent, and incorporated by reference here, is an ancillary feature of the present invention. The state of the art in the Potts device (1987) includes long established perforations 32 for fire grate 30, which grate may be an integral member, as depicted, or may be composed of two more grate modules that aid in loading of the device.
It is axiomatic with coal stoker type furnaces that much of the sensible heat provided by this exothermic coal combustion is wasted as it escapes the ambient area being warmed by the flue conduit gases venting to the outside. This has been confirmed by measured combustion gas temperatures in the flue of the Pottsxe2x80x94290 patent, ranging as high as 350 degrees F. It would be useful to capture more of the furnace generated heat that is now vented with combustion gases, provided that the efficiency of coal combustion, and the isolation of the toxic gases from the environment, can be maintained with an introduction of augmented sensible heat extraction means.
It is a principal object of the invention to provide a separate heat exchange means within stoker housing which efficiently extracts appreciably more sensible heat from the combustion gases just prior to their safe dispersal via the flue conduit, augmenting substantially the established radiant heating benefit.
It is a major object of the invention to provide a heat exchanger means disposed within a discrete second chamber that is hermetically sealed from the combustion-loaded gases flowing from of the first chamber.
It is still another object of the invention to draw toxic gases more uniformly from the combustion first chamber to a means for extracting much of their sensible heat normally being vented to the atmosphere for user safety.
A further object of the invention is to burn with a deeper fire bed, extracting greater sensible heat from the coal and producing ashes of a more powder-like consistency.
A still further object of the invention is to provide an ancillary induced air cooling means that reduces the surface temperature of the glassed access door and which further inhibits glass smudging by continuous air stream washing.
A further object of the invention is to provide a coal stoker serving as a mini-furnace whereby the extra sensible heat being generated in the improved stoker can also be funneled from the heat venting chamber via a separate conduit to another area, the heated air flow being within the power of the stoker convection blower means.
Other objects and advantages and features of the invention will be apparent to those skilled in the art from the following description taken in conjunction with the accompanying drawings and specification.